1. Field of the Invention
The invention relates to a tool for actuating the temporary lock-open mechanism of a safety valve adapted for downhole use in a subterranean well.
2. Description of the Prior Art
Safety valves, e.g. flappers, responsive to a pressure signal or wire line control are known in the art. A typical normally closed valve is held open during production by a plunger responsive to a fluid pressure control signal from the surface. When the control pressure is reduced, the plunger retracts, permitting the valve to close. It is often desirable for such a valve to have a releasable temporary lock-open feature, whereby the valve may be mechanically latched open without the necessity for a continuous pressure signal. Wire line equipment may then be run through the valve without danger of the valve being closed against such equipment.
In known types of tools three or four trips are required to set the temporary lock-open mechanism and then retrieve the tool which, of course, takes up wire line time and requires an inventory of many different types of tools. Accordingly, it is desirable to produce a lock-open tool which has the capability of engaging and actuating the temporary lock-open mechanism of the safety valve in one trip into the well, and being retrievable by wire line thereafter.